JPH1054840A - Flow velocity measuring method and flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily measure the average flow rate of a fluid with high accuracy even when the fluid is in an undeveloped state by measuring the flow velocity of the fluid in a plurality of directions at a plurality of measuring points and averaging the measured flow velocities in each direction, and then, multiplying the average flow velocity in each direction by a correction factor. SOLUTION: Many supporting bodies 2, on each of which flow velocity detecting elements 4x, 4y, and 4z directed in the x-, y-, and z-axis directions are arranged, are arranged at prescribed positions in the flow passage of a fluid so as to measure the flow velocity of the fluid in the x-, y-, and zaxis directions at the measuring points. The average flow velocity of the fluid in each direction is found by averaging the measured flow velocities of the fluid in each direction obtained at the measuring points and multiplying the average flow velocity in each direction by a correction factor, and then, averaging the corrected flow velocities. After the average flow velocity is found, the flow rate of the fluid is calculated. A thermal type flow velocity detecting element, turbine type flow velocity detecting element, etc., can be used as the flow velocity detecting elements. When the thermal type element is used, the element can be positioned easily in a gas pipe through a small inserting hole, because the flowmeter itself can be made extremely small in size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring method and a flow meter for measuring a flow rate of a fluid flowing in a pipeline. More specifically, the present invention relates to a flow velocity measuring method and a flow meter capable of accurately measuring a flow rate even under conditions where the flow is not developed.

[0002]

2. Description of the Related Art When measuring the flow rate of a fluid such as a gas or a liquid flowing in a pipe, if the fluid has irregular turbulence and the flow velocity distribution becomes non-uniform, an accurate flow rate cannot be measured. . In order to cope with this, conventionally, the flow of the fluid is set to a laminar state or a developed turbulent state,
The flow rate at a certain point was measured, and the flow rate was calculated based on the measured value, the known flow rate pattern, and the cross-sectional area of the flow path. In order to bring the fluid into such a laminar state or a developed turbulent state, the diameter of the pipe is 15 times the pipe diameter on the upstream side of the measurement point with respect to the pipe serving as the flow path. It is necessary to have a straight pipe structure having a length five times as long as the downstream side. However, in a conduit through which a fluid such as air, gas, or cooling water passes, it is almost impossible to secure such a long straight pipe portion in a state where the conduit is laid, which is not practically desirable. Was.

[0003] For this reason, as a flow measurement method in a case where such a straight pipe structure having a sufficient length cannot be ensured, a plurality of flow meters are required in order to enable flow measurement regardless of the state of fluid flow. Correlation-type flowmeters that suppress output fluctuations due to changes in flow velocity distribution in combination and measurement methods that structurally average the assumed values at multiple positions within the pipe cross-section and cancel these output fluctuations are used. Was.

For example, as a correlation type flow meter, Japanese Patent Publication No.
There is a Pitot tube flow meter described in US Pat. FIG. 14 is a partially cutaway perspective view showing the structure of the pitot tube flow meter, and FIG. 15 is a sectional view taken along line BB of FIG. This flow meter comprises a high pressure pipe 91 and a low pressure pipe 92.
And a high-pressure pipe and a low-pressure pipe are housed in a space inside a hollow sheath 93. A high-pressure port 94 and a low-pressure port 95 are opened at the ends of the low-pressure pipe 92 and the high-pressure pipe 91, respectively.
The low-pressure port 95 is disposed on the sheath so as to be located on the axis of the conduit into which the pitot tube is inserted, and the high-pressure port 94 communicates with a plurality of upstream ports 96 disposed on the upstream side of the sheath 93. The dynamic pressure from the plurality of upstream ports 96 is averaged and applied to the high pressure port 95. The pitot tube flowmeter having such a structure can obtain a stable and high S / N ratio output even when the straight pipe portion of the conduit is about several times the pipe diameter.

[0005] Recently, a thermal type flow rate detecting element using a semiconductor micromachining technique has been manufactured, and is extremely compact, and many elements can be arranged side by side on a measuring instrument. It has the advantage of being able to measure over a wide range and is being applied as a means of measuring these fluids. Moreover, the thermal flow velocity detecting element manufactured using this semiconductor fine processing technology has extremely high sensitivity,
For example, the flow rate can be measured over a wide range of 0.005 to 40 m / sec, the measurement can be performed with a response time of milliseconds (ms), and the measurement means does not affect the flow rate etc. It has excellent features such as not giving, low power consumption, and cost reduction by mass production.

FIG. 16 shows a flow meter using this flow rate detecting element.
In FIG. 16, the thermal type flow meter 1 includes a plurality of detecting elements 4 attached to a glass substrate 3 supported by a supporting member 2 such as a rope or stainless steel. The protective cover 5 is attached via a spacing member 6 and has a temperature detecting element 7. The contact pad 44 of each detecting element 4 is connected to the connecting pad 32 on the wiring pattern 31 side by a gold wire, and the terminal connecting pad 33 of the wiring pattern and the pad 34 of the temperature detecting element 7 are each connected to the signal via the connecting line 9. Connected to processing unit 8.

FIG. 17 shows a circuit configuration of the temperature detecting element and the signal processing section. In this example, the thermal flow velocity detecting elements 4-1 to 4-
3 shows a circuit configuration when n is connected in parallel. The signal processing unit 8 includes a constant voltage source 81, an arithmetic circuit 82, a display unit 83
And a voltage detecting resistor 84. As shown in the figure, a voltage Vc is applied to the heater wire of each element 4 via a voltage detecting resistor 84. Therefore, the current I flowing through the voltage detection resistor 8 is represented by the following equation.

[0008]

(Equation 1)

When the combined resistance of the heater wires 43-1 to 43-n is represented by r ', the voltage Vs appearing across the resistor 84 is expressed by the following equation. Vs = IsR = [Vc / (R + r ')] R = VcR / (R + r')

That is, the voltage V appearing across the resistor 84
Since s depends on the change in the combined resistance r 'of the heater wires 43-1 to 43-n, the change in the resistance of the thermal flow rate detecting element, that is, the change in the flow rate, can be measured from these electric signals.

In the flow rate measurement using such a thermal type flow velocity detecting element, a constant voltage Vc is applied to the connection between each thermal type flow velocity detecting element and the resistor 84, and the combined resistance of the heater wire in contact with the fluid is reduced. The current value flowing through the thermal flow velocity detecting element is detected by a change. The current flowing through the constant voltage power supply is equal to the sum of the current flowing through each detecting element 4 because the flow velocity detecting elements are connected in parallel. By making the current value flowing through the constant-voltage power supply equal to the output of the flow meter, an average value of the outputs of the thermal flow elements 4 can be obtained. In addition, according to this flow meter, since each element is connected in parallel, even if some elements are damaged, measurement can be performed by the remaining other elements, and the function is not immediately lost. And has excellent security features.

However, each of these flow meters can measure the flow velocity over a wide range in the flow path, but when the flow in the flow path is turbulent and cannot be patterned, the flow rate can be measured. Despite the accuracy of the measurements themselves, these measurements did not accurately represent the actual average flow rate. In other words, each flow meter and flow velocity detecting element directly averages the turbulent flow when the flow is not constant, or measures the flow velocity along the direction of the vortex flow such as Karman vortex in a micro area. Therefore, since these conditions are not constant depending on the position in the flow path, the flow velocity, and the like,
The method of simply averaging the flow state based on only the flow in the direction along the flow path or correcting the flow state with experimental values empirically patterned does not represent the actual flow rate.

In particular, in a pipe immediately after a measurement point such as a pressure regulator or a curved pipe, an irregular turbulent state accompanied by a vortex or a return flow occurs, so that the directional component does not become a fixed direction. However, the above measurement method could not eliminate the influence. Therefore, when using such a measurement method,
The measured flow rates were not always accurate and sufficiently reliable. To cope with this, when installing a flow meter in a gas pipe or the like to improve the accuracy in practice, it is necessary to make the pipe line as straight as possible to reduce the influence of turbulence as much as possible. In addition, since the measurement results obtained in this way are not expected to have high accuracy, a simple and high-accuracy flow rate measuring means has been desired.

[0014]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and has as its object to measure the average flow rate easily and with high accuracy even in a non-developed state. I do. Another object of the present invention is to provide a flowmeter excellent in security that can continuously measure without stopping the function by the remaining detection element even if the detection element is worn out or damaged. .

[0015]

According to the present invention, there is provided a method for measuring an average flow velocity of a fluid in a flow path, comprising the steps of: The flow velocity in at least two directions is measured, the flow velocity in each direction obtained at each of these measurement points is averaged, and the averaged value is multiplied by a correction coefficient for each direction to obtain a sum of the components in each direction. Find the average flow velocity. According to the second aspect of the present invention, the flow velocity is measured at each of the flow velocity measurement points using a thermal flow velocity detecting element. According to the third aspect of the present invention, the flow velocity is measured at each of the flow velocity measurement points using a turbine type flow velocity detecting element.

According to the present invention, the flow velocity measuring means is arranged so that the measuring direction is oriented in at least one direction different from the direction along the flow path direction, and the measuring means is oriented in each of these directions. And a flow rate detecting means in each direction formed by forming a plurality of measurement points in which a plurality of measurement points are arranged. According to a fourth aspect of the present invention, there is provided the flow meter according to the fourth aspect, wherein an output from each of the detecting means is averaged for each direction, and a calculation coefficient for each direction is multiplied to calculate a sum thereof. With. According to the invention of claim 6, according to claim 4,
In the flow meter described above, the flow velocity measuring means was covered with a direction component limiting cover having a U-shaped cross section. In the invention according to claim 7, in the flow meter according to claim 4, the flow velocity measuring means is a turbine type flow velocity detecting element. In the invention of claim 8, the flow velocity measuring means is mounted in the surface of the plate-shaped support having a thin surface in the flow direction of the fluid and in the opening connecting between both surfaces of the support. According to a ninth aspect of the present invention, in the flow meter according to the eighth aspect, the cross section of the support is streamlined.

That is, as described in the description of the prior art, the flow velocity detected by the thermal flow velocity detecting element or the like is:
Velocity along each direction, such as turbulent vortex at each measurement point, is an absolute value that does not take into account the direction, so if irregular turbulence occurs, it should be The average does not become the average flow velocity or the average flow rate in the direction along the flow path of the target fluid.

Therefore, in order to obtain highly accurate measured values, it is necessary to obtain and correct flow velocity components other than the flow path direction at these measurement points. Various properties representing the state of the fluid include temperature, pressure, and flow velocity. By measuring these changes, the flow direction and flow velocity of the fluid can be detected. For example, in the thermal type flow velocity detecting element, if the temperature change is caused to interfere with each other between two points and measured in a plurality of directions, the flow direction and the flow velocity can be known by detecting the temperature change in each direction. it can.

In this way, for example, along a cross section crossing a flow path, x, x in a plurality of specific directions, for example, in a flow path direction and two other directions perpendicular to the flow path direction.
As a three-dimensional coordinate system of y and z axes, the direction along the flow path is x
Two directions perpendicular to the axial direction and the flow path direction are defined as the y-axis and the z-axis, respectively, and the flow velocity of the fluid in each direction is measured. If measurement is performed for a plurality of measurement points, the directional component of the flow along the flow path in the cross section is determined from these measurement values. Therefore, flow velocities in the x-axis, y-axis, and z-axis directions are measured, a large amount of data is obtained in each direction, and a correction coefficient for each direction is determined by comparing the experimentally confirmed average flow velocity. Since significant turbulence has occurred in the flow path, it is predicted that not only the flow path direction but also a direction perpendicular to the flow path will change according to a specific condition according to a specific pattern. However, by introducing the measured values of the flow velocity in the y-axis and z-axis directions perpendicular to the flow path as well as in the flow path direction as parameters experimentally obtained, the influence of these turbulent flows can be reduced. The average flow velocity is obtained.

As a means for detecting such a change in the state of the fluid, there is a detection element for simultaneously detecting the flow velocity and the direction of the fluid by applying the principle of the thermal type flow velocity detection element described in the prior art. The structure of the detection element is shown in FIG. 10 and FIG. 11 in a cross-sectional view along the line AA. The detection element for detecting the flow velocity and direction of the fluid is configured by providing a pair of heater wires 43 on a protective film formed on a semiconductor substrate 41 such as silicon. A recess 45 is formed in the silicon substrate 41 on the back surface side of the heater wire 43 by etching or the like in order to easily transfer heat to the heater wire 43. A contact pad 44 for electrically connecting the heater wire 43 with a bonding wire such as gold is provided.

In order to detect the flow velocity and the direction of the flow using the thermal type flow velocity detecting element, the element is arranged in the fluid such that the direction of the flow crosses the pair of heater wires.
When a heating current is supplied to these heater wires, a temperature difference occurs between the upstream and downstream heater wires. By measuring the change in resistance due to the temperature difference, the direction and flow velocity of the flow across the pair of heater wires can be measured.

That is, when a pair of heater wires are energized to generate heat, the heater wires are cooled by the fluid, and their resistance values are changed according to the lowered temperature. Since the fluid is heated by the wire, a temperature difference occurs between the fluid and the upstream heater wire, and a difference occurs in the resistance value. Therefore, the flow direction can be detected from the difference between the resistance values of the pair of heater wires. At this time, it is also possible to detect the flow velocity of the fluid at the same time from the change in the electric resistance of the pair of heater wires as described above, and it is possible to know the flow velocity of the fluid in a predetermined direction from these measured values.

FIGS. 12 and 13 show another example of an element for detecting a change in the state of a fluid. This element can detect the flow rate in two directions, and is configured by providing two pairs of heater wires 43X and 43Z on a protective film formed on a semiconductor substrate 41 such as silicon. A recess 45 is formed in the silicon substrate 41 on the back surface side of the heater wire 43 by etching or the like in order to easily transfer heat to the heater wire 43. A contact pad 44 for electrically connecting the heater wire 43 with a bonding wire such as gold is provided.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to measure the flow velocity of a fluid in a three-dimensional three-dimensional direction using this detection element, as shown in FIG.
A flow velocity detecting element 4 along each of the x, y, and z axes
x, 4y, and 4z are arranged. By arranging a large number of the supports 2 provided with the flow velocity detecting elements at predetermined positions in the flow path, these x, y, and
The flow velocity in each direction of the z-axis can be measured.
Further, as shown in FIG. 2, each of the detection elements 4x, 4y, 4z
By providing the rectifying plate 10 that covers the flow direction, it is possible to avoid the influence of the flow other than the respective axial directions.

In order to measure the flow velocity and the direction of the flow by the heater wire 43, as shown in FIG.
The heater wires 43x, 43y,
43z may be arranged. Also in this case, since the temperature changes in the direction along the heater wire, the flow velocity in each axial direction can be measured. However, the accuracy can be improved by disposing the rectifying plate 10 shown by the broken line on the support 2. Can be.

In addition, a mechanical velocimeter such as a turbine can also be applied. As shown in FIG. 4, a turbine velocimeter 11x, 11x, 11x, By arranging 11y11z, it is possible to measure the flow velocity in each direction.

The flow velocities in the respective directions along the x, y, and z axes measured in this manner include a flow toward the x direction as a basic tone, and the flow of the flow as a turbulent component depends on its position and flow velocity. Since the directions are different, the flow components in the y- and z-axis directions other than the x-axis direction may also be measured, and the relationship between the experimentally confirmed average flow speed and the flow speed may be interpreted as these as parameters. Such turbulence in fluids is an extremely complex phenomenon, so it cannot be sufficiently analyzed even by simulation using a supercomputer, and access from strict fluid theory is practically difficult. It is possible to secure sufficient accuracy for practical use.

Therefore, the flow rates in the x, y, and z-axis directions thus measured are averaged for each measured value according to a conventional method, and multiplied by a correction coefficient experimentally obtained in each direction to obtain an average flow rate. What is necessary is just to obtain it as the sum. In this case, since the data obtained by these measuring means can be treated as an electrical output, the analysis and calculation thereof can be easily performed by the same method as the conventional measurement and calculation of the average flow velocity. it can.

Therefore, according to the present invention, not only the x-axis direction but also the flow velocity components in the x, y and z-axis directions in these flow paths are measured, and the influence of the flow in these directions due to turbulence is taken into account. Since the average flow velocity can be obtained, the turbulence occurs behind the pressure regulator, etc., and even if a sufficient flow path length cannot be secured, the presence of turbulence such as vortex at the measurement point Regardless, accurate average flow velocity measurements can be obtained.

[0030]

Next, a method for measuring the flow rate of a fluid using the thermal flow direction detecting element according to the present invention will be described with reference to a specific installation example. In FIG. 5, a gas pipe line in which the thermal flow meter 1 according to the present invention is installed is provided with a pressure regulator 52 for reducing the gas pressure to a 230 mm underwater gauge from a high pressure conduit 51 to which a gas of 7 kg / cm ² gauge is supplied. 750 mm with a diameter of 100 mm connected to the output side of the pressure regulator 52
Long conduit 52, 200 mm diameter and 2750 mm long conduit 5
It is connected to a conduit 55 having a diameter of 4 and 300 mm. The thermal flow meter 1 is inserted into a conduit of a conduit 54 through a small hole opened at a position 300 mm from a point enlarged from a diameter of 100 mm to a diameter of 200 mm of the conduit 53, and installed. At this location, the gas flow is in a non-developed turbulent state, since at most the diameter of the pressure regulator and conduit is less than three times its conduit diameter.

FIG. 6 shows details of a state in which the thermal type flow meter 1 is inserted into a conduit. A small hole for measurement provided with a screw at a predetermined position of the conduit 54 is provided, and the thermal flow meter 1 according to the present invention, in which the thermal detection element 4 is attached to the support 2, is sealed with a screw. . The thermal detection element 4 used in the present invention is 2
Since it has a small structure of about mm square, the overall size of the thermal flow meter is small and does not affect the resistance in the conduit.

FIG. 7 is an enlarged view of a portion surrounded by a chain line C in FIG. Each of the thermal detection elements 4x and 4z is connected to the flow meter 1 in a direction along the flow direction of the conduit and in a vertical direction in the drawing perpendicular to the flow direction.
Is attached on the support 2 along the surface of. Further, an opening 21 communicating left and right is provided on a side surface of the flow meter 1 in a direction perpendicular to the paper surface crossing the flow path, and the detecting element 4y is arranged along the horizontal axis in the opening. In the figure, the detection elements 4x and 4z in the direction of the flow path of the flow and the vertical direction perpendicular thereto are installed only on one surface of the flowmeter 1, but since the Karman vortices are generated symmetrically, they are arranged in such close proximity. In this case, only one side may be arranged for the detection.

FIG. 8 shows a section taken along the line AA of FIG.
The flow meter 1 is formed in a streamlined cross section so as not to disturb the state of the flow, is provided with openings 21 circulating on the left and right side surfaces thereof, and is configured to receive a flow such as a vortex along the left and right horizontal direction. . The thermal detection element 4y that is grounded in the opening 21 is arranged with the detection direction directed to the left and right horizontal direction, that is, the Y direction. FIG. 9 is a cross-sectional view taken along the line BB of FIG. 6, in which the thermal detection element 4x is arranged along one of the left and right surfaces along the flow path direction of the flow, and the other side is perpendicular to the flow. The thermal detection element 4z is arranged in the vertical direction. Such a combination of the detection element 4x in the flow direction and the detection element 4z in the direction perpendicular to the flow is alternately arranged on the left and right of the surface of the support, that is, the detection element 4x is arranged on one surface and the other surface is arranged. In the upper and lower positions where the detection element 4z is disposed, the measurement accuracy can be improved by disposing the detection element 4z on one surface and the detection element 4x on the other surface.

The structure of these flowmeters and the arrangement of the thermal detection elements are not limited to these examples, and the flowmeter having the elements arranged only on the flat portion of the support section 2 is mounted on the cross section of the conduit in the Y-axis direction. And components arranged vertically and horizontally in the Z-axis direction to measure the components of the flow Y-axis and the Z-axis in a direction perpendicular to the flow, in addition to the flow channel direction.

A method for obtaining the average flow velocity from the detection values thus detected will be described. As described above, when the thermal detection element for detecting a change in the state of the fluid is arranged in the respective directions with the flow path direction as the x axis and two directions perpendicular to the axis as the y and z axes, The element detects the flow velocity in each direction at the detection point. Therefore, averaging is performed for each of these directions. The averaging method may be a conventional method.

The data of the measured values in the x, y and z-axis directions are taken at a number of measurement points, and a correction coefficient for each direction axis is determined by comparing with the experimentally determined average flow velocity. Integrate the average flow velocity.

[0037]

(Equation 2) Here, α + β + γ = 1.0 is set, and x
_{1, x 2, x 3,} ... x n, y 1, y 2, y 3, ... y n, z 1,
z _2, z _3, is ... z _n, a velocity measurement at each x, y, the measurement points in the z-axis direction. α, β, and γ are flow velocity correction coefficients in the x, y, and z axis directions, respectively, and are experimentally obtained.

The average flow velocity can be obtained by the following equation (4). Average flow rate = X + Y + Z (4)

The thermal detection elements 4x, 4y, and 4z used in the present invention are not different from the thermal detection elements in terms of structure as an electric resistor, and are connected to a constant voltage source to supply electric power. Since it is a resistor that detects a change in electrical resistance, it can take the same parallel circuit configuration as in the case of the average flow rate calculation in the above-described prior art, even if individual detection elements are damaged under a severe use environment, By correcting the resistance value except for the damaged element, the measurement can be continued immediately without the measurement being disabled. Therefore, there is an advantage that the reliability is high in security management.

In the measurement by the thermal detection element 4, the response speed of the element is extremely fast, on the order of ms, as in the case of the above-mentioned conventional thermal detection element. Reading may be performed, and a sampling average may be obtained from these data, or a moving average having continuity by updating data every fixed number of times may be obtained.

In the above example, the thermal detection element and the temperature detection element are individually formed on a substrate. However, they are formed on a semiconductor substrate such as silicon by a fine processing technique such as photolithography. According to this method, the size of each element is extremely small, and a large number of elements can be accurately formed on the same substrate. Thus, it is possible to make it inexpensively.

[0042]

As described above, according to the present invention,
It is possible to accurately and easily measure the average flow rate of a fluid in a non-developed turbulent state. Further, since the flow meter can be constituted by a thermal detection element, the flow meter itself can be made extremely small, and can be easily attached to a gas pipe or the like through a small hole for insertion.

Further, according to the measuring method and the anemometer of the present invention, since the measuring accuracy is high, it is suitable for a wide range of uses such as detection of gas leakage and the like. The semiconductor microfabrication technology can produce remarkable functions and effects, such as being able to be formed on a silicon substrate or the like, being extremely compact, and being capable of significantly reducing costs by mass production effects.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of the arrangement of detection elements in a flow meter according to the present invention.

FIG. 2 is a conceptual diagram showing another example of the installation example of the detection element in the flow meter according to the present invention.

FIG. 3 is a conceptual diagram showing an example of the arrangement of heater linear detection elements in a flow meter according to the present invention.

FIG. 4 is a conceptual diagram showing an example of the arrangement of a turbine velocimeter in the flowmeter according to the present invention.

FIG. 5 is a diagram showing an example in which a flow meter according to the present invention is installed in a pipe.

FIG. 6 is a sectional view showing a state where the flow meter according to the present invention is installed in a pipe.

FIG. 7 is an enlarged view of a portion surrounded by a chain line C in FIG. 6;

FIG. 8 is a sectional view taken along line AA of FIG. 6;

FIG. 9 is a sectional view taken along line BB of FIG. 6;

FIG. 10 is a plan view of a thermal detection element used in the present invention.

FIG. 11 is a sectional view taken along line AA of FIG. 10;

FIG. 12 is a plan view of a two-way detection type thermal detection element used in the present invention.

FIG. 13 is a sectional view taken along line BB of FIG. 12;

FIG. 14 is a perspective view showing a configuration of a conventional Pitot tube correlation flow meter.

FIG. 15 is a sectional view taken along line BB of FIG. 14;

FIG. 16 is a perspective view showing a configuration of a flow meter using a conventional thermal flow velocity detecting element.

FIG. 17 is a circuit diagram for calculating a flow rate using a conventional thermal type flow velocity detecting element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal flow meter 2 Support member 3 Glass substrate 4 Thermal detection element 5 Protective cover 6 Spacing member 7 Temperature detection element 8 Signal processing unit 9 Connection line 10 Rectifier plate 11 Turbine velocity meter 21 Small hole 31 Wiring pattern 32 Wiring Pattern side connection pad 33 connection terminal pad 34 temperature detection element pad 41 silicon substrate 43 heater wire 44 contact pad 45 recess 46 gold wire 51 high pressure conduit 52 pressure regulator 53 conduit (100 mm diameter) 54 conduit (200 mm diameter) 55 conduit ( 81 constant voltage source 82 arithmetic circuit 83 display unit 84 voltage detection resistor 90 pitot tube 91 high pressure tube 92 low pressure tube 93 sheath 94 high pressure port 95 low pressure port 96 upstream port

Claims (9)

[Claims] In a flow velocity measuring method for measuring an average flow velocity in a turbulent flow path, a flow velocity in at least two directions is measured at a plurality of measurement points in a fluid, and the flow velocity is obtained at each of these measurement points. A flow velocity measurement method for averaging the flow velocity in each direction, and calculating an average flow velocity as a sum of values of each direction component obtained by multiplying the averaged value by a correction coefficient for each direction. 2. The flow velocity measuring method according to claim 1, wherein the flow velocity at each measurement point is detected by a thermal flow velocity detecting element. 3. The flow velocity measuring method according to claim 1, wherein the flow velocity at each measurement point is detected by a turbine type flow velocity detecting element. 4. The method according to claim 1, further comprising arranging the flow velocity measuring means so that the measuring direction is oriented in at least one direction different from the direction along the flow path direction, and comprising flow velocity measuring means in each of these directions. Flow meter. 5. The flow rate according to claim 4, further comprising an arithmetic means for averaging the output from each detecting means for each direction, multiplying by a correction coefficient for each direction, and calculating the sum thereof. Total. 6. The flow meter according to claim 4, wherein the flow rate measuring means is covered with a direction component limiting cover having a U-shaped cross section. 7. The flow meter according to claim 4, wherein the flow rate measuring means is a turbine type flow rate detecting element. 8. The apparatus according to claim 4, wherein the flow velocity measuring means is mounted in a surface of a plate-shaped support having a thin surface in a flow direction of the fluid and in an opening connecting between both surfaces of the support. Flowmeter as described. 9. The flow meter according to claim 8, wherein the cross section of the support is streamlined.